Coupling agents are chemical compounds capable of reacting to form chemical bonds with both the reinforcement and the resin matrix of a composite material. It may also bond inorganic fillers or fibers to organic resins to form or promote a stronger bond at the interface. Coupling agents may be applied in solution or gas phase to the reinforcement, added to the resin, or both. The coupling agent acts as the interface between resin and mineral to form a chemical bridge between the two. The most common classes of coupling agents are silane coupling agents (e.g., organotrialkoxysilanes), titanates, zirconates, and organic acid-chromium chlorides coordination complexes.
Coupling agents are commonly used in the manufacture of abrasive articles (e.g., coated abrasive articles, resin-boned abrasive articles, and nonwoven abrasive articles) to chemically bond the abrasive mineral and filler to the polymeric binder resin.
However, various inadequacies may exist when using coupling agents with common abrasive minerals, typically in the form of abrasive grain or abrasive particles. For example, the bonding strength between the mineral and the resin may be insufficient for use conditions, resulting in premature loss of abrasive grain in a phenomenon known as shelling. Further, coupling agents may not be suitable for use with abrasive grain (e.g., diamond and cubic boron nitride) that has few if any reactive groups on its surface.
There remains a need for methods and materials that increase the bonding between abrasive grain and binder resin in abrasive articles.